The spanning tree protocol is a Layer 2 management protocol, which network by selectively blocking the purpose of eliminating redundant links to the network Layer 2 loops, along with backup link.
As the spanning tree protocol itself is relatively small, it is not as well known as the routing protocol. But it rules the power port forwarding - "small branches shake, upper-layer protocols have another way of living." The real situation is also true, especially when together with other protocols running, it is possible to cut off the other spanning tree protocol packets path, causing all sorts of strange phenomenon.
Spanning Tree Protocol and other protocols, with the continuous development of the network and the continuous upgrading. The title of this article "spanning tree protocol" is a broad concept, the STP IEEE 802.1D not especially defined, but includes STP and various enhanced on the basis of the STP spanning tree protocol.